In addition, I do not like how Vivaldi and other chromium based browsers auto-populate the login fields when on a login page. I prefer how old Opera handled it; nothing appears until you hit either ctrl+enter or the wand button. Please bring this into Vivaldi, simply because it adds that one small extra layer of safety.

Vivaldi is already very customizable.
It uses web technologies to display the UI, so a lot of things can be changed by just modifying a .css file (and for more complex customization involving the structure the bundle.js can be modified)
Buttons can be hidden or repositioned, shapes and colors changed, animations added, etc, etc.
The interface is just like any other web page.
Here is one example, what can be accomplished:
https://vivaldi.net/forum/all/1329-a-white-skin

Hello,
To be clear about the Linux comments, they were mostly useless and off-topic… that's a Linux user who say that.
Maybe there was too much censorship on the other things, I don't know, but I prefer upvote system for usefull comments.
An upvote system can HighLight the most requested things.